Anyone know if there are any DIY plans online for building a dolly similar to this one?
Round-d-Round Doorway Dolly by Matthews CAT 395300 (http://www.filmtools.com/rounddround.html)

Thanks!

Here is on similar that is pretty cool

4 WHEEL STEERING Diamond 360* Film Video Doorway Dolly - eBay (item 280428238916 end time Nov-26-09 11:36:22 PST) (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&Item=280428238916&Category=3319)

I was thinking of going with the round d- round, but this one is half the price.
Anyone used a Diamond Dolly before?

What ever you do, DO NOT go with the Diamond Doorway Dolly... Do not believe their high ratings and positive reviews on Ebay, they are all lies. There are several complains out there about people being scammed by them and never receiving their items or getting their dolly with missing/broken parts and having to wait several months to receive anything.

Matthews dollies are pretty heavy duty and well constructed. If you're of an engineering bent the traditional doorway should be manageable, although you may need to check out a suitable modified steering system from say a go kart. There's a fair amount of welding and some machining in these dollies.

I suspect the steering system on the new doorway is a bit more complex. Although looking at the diamond you can see how it works, however, you may need to have a jig to ensure an accurate alignment of the wheels.